Scientists have identified a gene that can triple the risk of a child developing a peanut allergy.

The gene - Filaggrin - helps make the skin a barrier against irritants and allergens. But changes in the gene limit its effectiveness to do this, allowing allergens to enter the body, causing a reaction. The gene is also a factor in eczema and asthma.

The study, published in the Journal of Allergy and Clinical Immunology, suggests 20% of all peanut allergy sufferers have a Filaggrin defect. Those with the gene defect are up to three times more likely to suffer a peanut allergy than people with normal Filaggrin.

Dundee University's Professor Irwin McLean, a leading expert on Filaggrin said:

"We knew that people with a Filaggrin defect were likely to suffer from eczema, and that many of those people also had peanut allergy.

"What we have now shown is that the Filaggrin defect is there for people who have peanut allergy but who don't have eczema, which shows a clear link between Filaggrin and peanut allergy."